Does Beta-Carotene Preserve Memory?
Study Shows Supplements May Help Keep Thinking Skills Sharp
Nov. 12, 2007 -- Beta-carotene supplements, when taken for many years, may
preserve memory and other thinking skills, perhaps reducing the risk of
dementia, according to a new study.
But even the study researchers recommend caution in interpreting the
results, emphasizing that the improvement from the supplements was modest for
"Long-term beta-carotene had the effect of delaying changes in their
memory by about a year," says Francine Grodstein, ScD, associate professor
of medicine at Harvard Medical School and associate epidemiologist at Brigham
& Women's Hospital in Boston, who led the study.
Other experts familiar with the new research say the study is no reason to
begin taking supplements of beta-carotene simply to avoid dementia.
The antioxidant is also found in red, orange, and yellow fruits and
vegetables, including sweet potatoes, mangoes, and cantaloupe.
Beta-Carotene and Memory
Long-term oxidative stress caused by "free radical" compounds
circulating in the blood is thought to be a major factor in many health
problems, including a decline in cognitive functioning. Decreased cognitive
functioning, in turn, is thought to strongly predict the development of
So researchers are focusing on beta-carotene and other antioxidants, trying
to find out if high intake or high blood levels can prevent the oxidative
stress. Findings so far have been mixed.
In the study, Grodstein and her co-researchers evaluated the effects of
beta-carotene or placebo on cognitive abilities in nearly 6,000 men, including
those who participated long term and short term.
The long-term group included 4,052 men who had been taking either 50
milligrams of beta-carotene or a placebo tablet every other day from 1982 to
1995 as participants in the Physicians' Health Study. The study was originally
designed to look at the effect of beta-carotene, aspirin, and placebo on heart
disease and cancer, and when the beta-carotene arm ended in 1995, researchers
had found no effect on either disease from beta-carotene.
Some of the participants agreed to join the sequel study, Physicians' Health
Study II, beginning in 1997, and kept their original assignments to take either
beta-carotene or placebo.
An additional 1,904 men, new recruits, were assigned to take either the
supplement or placebo, joining between 1998 and 2001.
The men were all in good health when they started the studies. Those who had
taken part in the original study were about age 73 when the sequel study began;
the new recruits were about 56 on average.
The men were followed up through 2003, completing yearly questionnaires
about their health and their compliance with taking the pills. Their cognitive
functioning was tested by telephone at least once between 1998 and 2002.
"The focus was on verbal memory," Grodstein tells WebMD. For
instance, researchers would read a list of words and ask the participants to
read them back immediately and again 20 minutes later.